Disinfection byproducts
HAA5 in U.S. tap water
1,113 public water systems across 43 U.S. states report HAA5 in their annual Consumer Confidence Report. 34 sit at or above the federal limit.
What it is
Haloacetic acids — a group of five disinfection byproducts formed when disinfectants react with organic matter.
Why it's regulated
Long-term exposure above the federal limit is associated with an increased cancer risk.
At or above the federal limit (34)
| Water system | Measured | vs. limit |
|---|---|---|
| Muscoy Mwc No. 1 — San Bernardino, Ca, CA 2023 annual report | 1 mg/L | 16.7× the limit |
| City of Parlier — Parlier, Ca, CA 2023 annual report | 0.67–0.76 mg/L | 12.7× the limit |
| Willow County Water District — Ukiah, Ca, CA 2021 annual report | 603 ug/L | 10.1× the limit |
| City of Newman-water Department — Newman, Ca, CA 2023 annual report | 0.3 mg/L | 5.0× the limit |
| Glen Helen Water System — San Bernardino, Ca, CA 2023 annual report | 0.17 mg/L | 2.8× the limit |
| Macon, GA 2023 annual report | 10.6–132.6 ug/L | 2.2× the limit |
| Alco Water Service — Salinas, Ca, CA 2023 annual report | 0.13 mg/L | 2.2× the limit |
| Hialeah, FL 2023 annual report | 46.52–98 ug/L | 1.6× the limit |
| Jackson, MS 2024 annual report | 14.4–97.3 ug/L | 1.6× the limit |
| Nacimiento Water Company — Bradley, Ca, CA 2023 annual report | 46–96 ug/L | 1.6× the limit |
| Laredo, TX 2024 annual report | 16.9–82.5 ug/L | 1.4× the limit |
| City of Hialeah, FL 2023 annual report | 3–81 ug/L | 1.4× the limit |
| City of North Miami Beach, FL 2023 annual report | 3–81 ug/L | 1.4× the limit |
| Miami Dade, FL 2023 annual report | 3–81 ug/L | 1.4× the limit |
| Cdcr California Health Care Facility — Stockton, Ca, CA 2023 annual report | 12–78 ug/L | 1.3× the limit |
| High Point, NC 2024 annual report | 78 ug/L | 1.3× the limit |
| Heritage Ranch Csd — Paso Robles, Ca, CA 2023 annual report | 33–76 ug/L | 1.3× the limit |
| Yonkers, NY 2024 annual report | 11.8–74.3 ug/L | 1.2× the limit |
| Springfield, MA 2024 annual report | 43–71 ug/L | 1.2× the limit |
| Brophytown Distribution System, MD 2024 annual report | 36.5–68.1 ug/L | 1.1× the limit |
| Sweetwater Authority — Chula Vista, Ca, CA 2023 annual report | 0–66.4 ug/L | 1.1× the limit |
| Billings, MT 2024 annual report | 17–66 ug/L | 1.1× the limit |
| Calistoga, City of — Calistoga, Ca, CA 2021 annual report | 35–65 ug/L | 1.1× the limit |
| Columbia, SC 2024 annual report | 11–65 ug/L | 1.1× the limit |
| Freedom District, MD 2024 annual report | 22–64.6 ug/L | 1.1× the limit |
| Topeka, KS 2024 annual report | 10–64.2 ug/L | 1.1× the limit |
| Pismo Beach Water Department — Pismo Beach, Ca, CA 2023 annual report | 64 ug/L | 1.1× the limit |
| Brunswick, MD 2024 annual report | 22.22–63.66 ug/L | 1.1× the limit |
| Lake Elizabeth Mutual Water Co. — Elizabeth Lake, Ca, CA 2023 annual report | 0–63 ug/L | 1.1× the limit |
| Santa Cruz Water Department — Santa Cruz, Ca, CA 2023 annual report | 2–62 ug/L | 1.0× the limit |
| St. Helena, City of — St. Helena, Ca, CA 2023 annual report | 61.71 ug/L | 1.0× the limit |
| Coral Springs, FL 2024 annual report | 0.29–61 ug/L | 1.0× the limit |
| City of West Sacramento — West Sacramento, Ca, CA 2022 annual report | 60 ug/L | 1.0× the limit |
| Frisco, TX 2024 annual report | 60 ug/L | 1.0× the limit |
Approaching the limit (25)
| Water system | Measured | vs. limit |
|---|---|---|
| Purissima Hills Water District — Los Altos Hills, Ca, CA 2022 annual report | 59.9 ug/L | 1.0× the limit |
| Greensboro, NC 2024 annual report | 59 ug/L | 1.0× the limit |
| Nevada Id - Lake Wildwood — Grass Valley, Ca, CA 2020 annual report | 14–57 ug/L | 1.0× the limit |
| Nps-wolverton — Three Rivers, Ca, CA 2023 annual report | 56.5 ug/L | 0.9× the limit |
| Akron, OH 2024 annual report | 30.9–55.1 ug/L | 0.9× the limit |
| City of Pleasanton — Pleasanton, Ca, CA 2023 annual report | 55 ug/L | 0.9× the limit |
| Casitas Municipal Water Dist — Oak View, Ca, CA 2023 annual report | 54 ug/L | 0.9× the limit |
| Reno, NV 2024 annual report | 54 ug/L | 0.9× the limit |
| Ventura River Water District — Ojai, Ca, CA 2023 annual report | 54 ug/L | 0.9× the limit |
| West Valley City, UT 2024 annual report | 53 ug/L | 0.9× the limit |
| West Jordan, UT 2024 annual report | 52.07 ug/L | 0.9× the limit |
| San Jose Water — San Jose, Ca, CA 2021 annual report | 52 ug/L | 0.9× the limit |
| Georgetown Divide Pud — Georgetown, Ca, CA 2022 annual report | 10.5–51.6 ug/L | 0.9× the limit |
| City of Lathrop — Lathrop, Ca, CA 2023 annual report | 22–51 ug/L | 0.9× the limit |
| Stamford, CT 2024 annual report | 51 ug/L | 0.9× the limit |
| Worcester, MA 2024 annual report | 16–51 ug/L | 0.9× the limit |
| Athens, GA 2024 annual report | 0–50.5 ug/L | 0.8× the limit |
| East Bay Mud (ebmud) — Oakland, Ca, CA 2023 annual report | 50 ug/L | 0.8× the limit |
| Thermalito Water & Sewer Dist — Oroville, Ca, CA 2023 annual report | 35–50 ug/L | 0.8× the limit |
| Augusta, GA 2024 annual report | 49.32 ug/L | 0.8× the limit |
| Avenal, City of — Avenal, Ca, CA 2023 annual report | 25.17–49.2 ug/L | 0.8× the limit |
| Citrus Heights Water District — Citrus Heights, Ca, CA 2023 annual report | 49.1 ug/L | 0.8× the limit |
| Fair Oaks Water District — Fair Oaks, Ca, CA 2022 annual report | 49.1 ug/L | 0.8× the limit |
| Lemoore, City of — Lemoore, Ca, CA 2023 annual report | 49 ug/L | 0.8× the limit |
| San Luis Obispo Water Department — San Luis Obispo, Ca, CA 2023 annual report | 21–49 ug/L | 0.8× the limit |
Within the federal limit (1054)
Showing 50 of 1054. The full list is in the JSON API.
Frequently asked
+What is HAA5?
Haloacetic acids — a group of five disinfection byproducts formed when disinfectants react with organic matter. Long-term exposure above the federal limit is associated with an increased cancer risk.
+What is the federal limit for HAA5 in drinking water?
The federal MCL for HAA5 is 60 ug/L. The EPA enforces this against the regulated reporting statistic (typically a running annual average or 90th percentile), not a single-sample spike.
+How many U.S. water systems have HAA5 over the federal limit?
34 of the 1113 public water systems on The Water Map report HAA5 at or above its federal limit, spanning 43 U.S. states. The full list is on this page.
+How can I check if HAA5 is in my city's tap water?
Search your city on The Water Map (https://www.thewatermap.com/) or browse the list on this page. Every U.S. public water utility is required to publish an annual Consumer Confidence Report that lists every contaminant it measured, including HAA5.